HS2 has limited its plans to passenger traffic, I don't know why. But economic development is an important aim and there must be economic value in transport which could get a computer spare or a vaccine from one end of the country to the other in under 3 hours.

The opportunities have been seized in another field.

Many modern aircraft are designed so that at times of slack passenger traffic, the seats can be pulled to one end and freight put into their place. The Boeing 747 - 400M "Combi" provides an example of this. Freight forwarders pay much higher prices for high-speed carriage of parcels preferring air to cheaper land transport, and if we are thinking of a high-speed railway to pull passengers from air, we should think of the same for parcels. There is huge amount of this traffic, medicines, electronics, newspapers, cut flowers, fronted by specialist carriers, the Post Office, FedExpress, UPS, etc. We would like to use the full passenger capacity of the train for peak time service and use part of the train for carrying freight out of the peaks.

I was surprised to find myself driven to the conclusion that the freight should be carried on the upper deck of double-deck trains because that would allow unbroken walk-through on the lower deck and the loading/unloading equipment would be hung from the ceiling of the station and so not obstruct passenger movement along the platform. In the routing scheme I outline below, only the Liverpool circular trains are turned around, all the others will have the same ends at the north end of Euston, and that can be the end used as needed for freight.

The upstairs floor of the train is fitted with a grid of low rails, in a grid pattern to guide the units to their correct places. Though the rails may be only a centimetre high, this is a miniature railway and the standard thinking of flanges and crossings applies. The floor the rails stand on does not need to be suitable for walking on.

A unit carrying two seats side-by-side would be a very suitable size for cargo-carrying units though other sizes might be possible. Seat-carrying units and cargo-carrying units are motored to place and locked in place in exactly the same way.

Seat-carrying units will have a square panel of flooring around them, these panels will abut onto the panels of other seat-carrying units to form a continuous floor of whatever surface is wanted for the passengers. The equipment built into each unit will be:-

* Fore-and-aft drive, which is lowered to fit onto the fore-and-aft rails and motors fore-and-aft as required. It is lifted when not required.

* Sideways drive, which is lowered to fit onto the sideways rails and motors sideways as required. It is lifted when not required.

* A lock, which fastens the unit down when the unit has reached the wanted place. It may also plug in electrical connections for such things as the lights overhead (which are not moved) or a power supply for refrigerated or heated cargo.

We would want passenger units to be locked into place when the train is moving, but it would be a great advantage to allow cargo-carrying units to be motored around so that the right ones are in place for unloading at the next stop.

Alternatively, the sideways and lengthways rails might be laid like smaller-size tramway rails in the passenger flooring, with rubber inlay to stop small objects from falling into the groove. The convenient way to get the units on and off the train is obviously sideways through the doors. Trains can be brought to a fairly exact stop; the rails in the loading ramp can be bent enough, left or right, to mate exactly with the rails in the train.

Once out of the train, seat-carrying units may be motored to parking or cleaning facilities and cargo-carrying units may be motored to appropriate facilities. The passage might be quite long and allow moderate speeds, curvatures and gradients as on any railway. And so the cargo-carrying carriers can be routed to the delivery offices or in the case of really large users, directly into their promises.

The ability to change the seating might be used to make quite drastic changes, for example, sleeping arrangements rather than daytime seating. The airlines have shown original thinking in this respect.